Obtaining and using materials and energy
Responding to the environment
Growth and development
Reproduction
Homeostasis
Evolution
To obtain and use materials and energy, organisms rely on various mechanisms and processes. Here are the steps involved in obtaining and using materials and energy:
1. Obtaining materials and energy:
- Autotrophs: Autotrophic organisms, such as plants, algae, and some bacteria, can produce their own food through processes like photosynthesis or chemosynthesis. They use sunlight or chemicals as a source of energy to convert inorganic substances (e.g., carbon dioxide, water, and minerals) into organic compounds (e.g., glucose) that can be used for growth and energy.
- Heterotrophs: Heterotrophic organisms cannot produce their own food and rely on other organisms for their nutrition. They obtain materials and energy by consuming organic matter, such as plants (herbivores), other animals (carnivores and omnivores), or a combination of both. Heterotrophs break down complex organic molecules into simpler ones through processes like digestion.
2. Digestion and absorption:
- Ingestion: Heterotrophs ingest food through various methods, such as chewing, swallowing, or engulfing.
- Digestion: Once food is ingested, it undergoes digestion, where complex macromolecules (e.g., carbohydrates, proteins, and lipids) are broken down into smaller molecules (e.g., glucose, amino acids, and fatty acids) that can be absorbed and used by cells.
- Absorption: Small nutrient molecules are absorbed through the walls of the digestive tract and enter the circulatory system, which then transports these molecules to the body's cells.
3. Cellular respiration:
- Organisms use cellular respiration to convert the chemical energy stored in nutrients (e.g., glucose) into ATP (adenosine triphosphate), which is the energy currency of cells. Cellular respiration occurs in the mitochondria of eukaryotic cells and can happen aerobically (using oxygen) or anaerobically (without oxygen), depending on the organism and environmental conditions.
When responding to the environment, organisms exhibit various behaviors and physiological responses. Here are some typical responses:
1. External stimuli detection:
- Organisms have sensory systems (e.g., vision, hearing, taste, touch, smell) that enable them to detect and respond to external stimuli, such as light, sound, chemicals, temperature, and pressure.
2. Processing of stimuli:
- Upon receiving sensory input, organisms process this information in their nervous systems or sensory organs. They analyze and interpret the stimuli and determine the appropriate response.
3. Behavioral responses:
- Organisms can exhibit behavioral responses to stimuli. For example, animals may change their movement or position, seek or avoid certain environments, or display specific actions or behaviors to adapt to the environment's demands.
4. Physiological responses:
- Physiological responses involve changes within an organism's body systems. These responses are usually automatic and aimed to maintain homeostasis (internal stability) in response to environmental changes. Examples include changes in heart rate, blood flow, hormone release, and body temperature regulation.
5. Developmental responses:
- Some organisms undergo developmental responses to environmental cues. These responses can include changing their structure, appearance, or behavior at different stages of their life cycle to optimize survival and reproduction.
Overall, obtaining and using materials and energy and responding to the environment are essential processes for organisms to survive and thrive in diverse habitats.